Vision screening system

ABSTRACT

A method for detecting the presence of eye disease in a human eye. A test subject is presented with a fixation target positioned on a colored planar surface. The test subject focuses a test eye on the fixation target and positions the test eye a sufficient separation distance from the fixation target and aligns the test eye relative to said fixation target so that the test subject&#39;s central and peripheral visual health can be tested. Additional marks are presented on the planar surface for detection by said test subject using the peripheral vision of the test eye. The additional marks are primarily the same level of black-white contrast as the planar surface but different in hue to create color contrast symbols, and are presented within the field of vision of an eye not afflicted with the disease for which testing is being conducted. In this way, the presence of eye disease can be detected if the additional marks are not visible to the test subject.

BACKGROUND OF THE INVENTION

The present invention relates to a novel vision screening system. Moreparticularly, the present invention relates to a method and relatedapparatus for detecting eye disease that may be easily and convenientlyadministered to a test subject without the need for trained personnel orspecialized equipment not readily available outside a medical office.

Glaucoma and diabetic eye disease are prevalent afflictions of the eyethat can occur in anyone at any time and can lead to permanent loss ofvision. By far, the most common type of glaucoma is chronic simpleglaucoma which is painless, slowly progressive and virtuallyundetectable by the individual particularly in its stages when it ismost easily and successfully treated. Most individuals with glaucomaonly become aware of it at a time when all that remains in one or botheyes is tunnel vision due to its gradual, painless and progressivecourse when left untreated. The same is true for other diseasesassociated with abnormalities of the field of vision, including but notlimited to diabetic eye disease and certain brain tumors.

With normal peripheral vision, at any given distance from the eye, ablind spot exists at a predetermined distance just temporal to a targetpoint at which the eye is fixated. Most of the earliest scotomas inglaucoma (i.e., small circumscribed areas ranging from dimness tocompletely blacked-out areas of visual field) occur in a narrow regionradiating generally arcuately from just outside this blind spot aboveand below the point of fixation. Advanced glaucoma changes are presentwhen multiple scotomas in this region begin to coalesce after which theyextend beyond the region itself and eventually encroach on or eliminatecentral vision. Prior to actual loss of central visual acuity is anonspecific decrease in central vision contrast discrimination. In earlydiabetes, areas in close proximity to the foveal vision develop discreteareas of tissue damage leading to receptor dysfunction or failure, oftencoalescing due to fluid leakage draining according to anatomicalchannels towards the foveal vision. Typical to early diabetes then areareas surrounding the central visual field, usually within a 10 degreecone angle, with discrete areas of tissue damage and dysfunction. Theseareas can continue to dim, surrounding sharp central vision, soonaffecting central contrast vision, until eventually the central visionand its best acuity itself are reduced.

Most of today's methods of visual testing for peripheral vision lossfrom glaucoma and other diseases require sophisticated devices toaccurately create a peripheral vision map, which is a graphic depictionof the extent of the field of vision, with any areas in which peripheralvision is diminished or absent well demarcated. These tests requirespecialized equipment, use of a trained technician, and have associatedwith them the problem of maintaining fixation. That is, in order to testperipheral vision, the test subject must maintain focus on a centraltarget; failure to do so invalidates that particular peripheral visiontesting sequence, and if occurring frequently enough, invalidates theaccuracy of the test.

In addition, since these tests are not self-tests, the diabetic field ofvision test, known as a macular, or 10 degree field of vision test, israrely used, with preference for angiographic study of the retinalcirculation, the retina being the affected tissue layer at the back ofthe eye in diabetes. A self-test assessing the health of the visualfield as well as foveal vision could allow early awareness of diabeticeye disease within the home, prior to the permanent loss of centralvision which now is frequently the earliest warning sign one afflictedwith the disease will have.

One of the peripheral vision tests which has long been used, the tangentscreen, is a simple test, but it too has the same fixation problem andrequires a technician. Other tests of this nature include manual andautomated perimetry. These visual field tests also require a technicianto administer the test, and use highly specialized equipment. Thepatient looks at a central fixation target within a hollowed-out dome,and indicates when a light can be seen with side vision. While thesetests can be very accurate, they are often difficult to administerproperly since they are tedious--often taking twenty minutes or more pereye--and it is difficult to completely prevent the patient from lookingdirectly at the source of light which is the peripheral target ratherthan remaining fixed on a central target and using side vision to detectthe light. A trained observer views the test taker's pupil, and warnsthe test subject when movement of the eye is observed--the standardmeans of trying to maintain fixation. Such tests also typically requirethe use of special equipment that tends to be rather large and bulky.

About one person in five with normal visual health is unable toadequately follow the instructions discussed above to provide for usefultest information. This translates to nearly one person in three in apopulation of glaucoma patients, where such testing is especiallyimportant for both initial diagnosis and monitoring. Of the millions ofAmericans at risk for glaucoma, only a relatively small fraction of thispopulation is seen by eye professionals in a given year, and only aportion of the individuals who obtain professional assistance receivesuch sophisticated testing. Diabetic eye disease and glaucoma, the twoleading treatable causes of blindness, are frequently first discoveredafter vision loss becomes sufficiently advanced to have caused permanentnoticeable vision loss. Due to its gradual onset this may bemisinterpreted as a glasses problem, and examination delayed. Toofrequently, by the time diagnosis and treatment begins, considerableirreversible damage exists in one or both eyes, and treatment is moredifficult and less vision can be saved. Earlier diagnosis andintervention before vision loss is detectable by the human eye wouldgreatly increase the successful treatment of these diseases, anddecrease the need for complex surgical intervention that is required foradvanced cases.

My U.S. Pat. No. 5,061,059 entitled "Self-Detection Glaucoma TestMethod," which is incorporated into this disclosure by reference,describes a novel method test method for self-detection of eye disease.Indeed, the test method described in my patent is relatively easy andconvenient to use without the need for expensive equipment or atechnician.

An improved test method, however, might further enhance the ability totest for eye disease with improved accuracy, allow assessment of centralas well as peripheral visual health, improve fixation compliance,provide testing instructions in a convenient manner, provide forself-demonstration, interactive test subject training, and interactivereview of test-taking proficiency. Further, an improved test methodmight, at the same time, be easy to use, convenient, and relativelyentertaining. It is therefore an object of the present invention toprovide an improved eye disease self-test method that further enhancesthe ability to detect eye disease and is also easy to use, convenient,and relatively entertaining.

Other objects and advantages of the present invention will becomeapparent from the ensuing description.

SUMMARY OF THE INVENTION

The present invention is directed to a novel test method and devices fordetecting the presence of eye disease in the human eye, such as glaucomaor diabetic eye disease for example. The inventive method provides aneasy to use and convenient test method for sensitive detection of earlyeye disease that can be conducted either inside or outside the medicaloffice using equipment that is readily available to the averageconsumer.

The present invention provides a sensitive and accurate method fordetecting the presence of eye disease in a human eye wherein a testsubject is presented with a fixation target positioned on a coloredplanar surface. The test subject focuses a test eye on the fixationtarget and positions the test eye a sufficient separation distance fromthe fixation target and aligns the test eye relative to said fixationtarget so that the test subject's peripheral vision can be tested.Additional marks are presented on the planar surface for detection bysaid test subject using the peripheral vision of the test eye. Theadditional marks are of a low color contrast relative to the backgroundplanar surface to create low color contrast symbols, and are presentedwithin the field of vision of an eye for which testing is beingconducted. In this way, the presence of eye disease can be detected ifthe additional marks are not visible to the test subject.

The preferred test method can be administered with the aid of a homepersonal computer system, or video equipment such as a television andvideo cassette player or the like. In this way the test may be conductedin an environment that can provide the test subject with appropriateinstructions and guidance to help ensure that the test format andprocedure is clear to the test subject throughout the entire test. Thetest method may also provide for quick and easy review of the testresults so that the test subject may be presented with an indication ofthe test subject's risk of disease. Further, the preferred test methodmay includes new devices and procedures for proper positioning of thetest subject relative to the test field, as well as devices andprocedures for assisting the test subject in adjusting the testing roomlighting to an appropriate level, procedures to monitor the testsubject's compliance with testing procedures, and devices for monitoringand enforcing the test subject's point of fixation.

BRIEF DESCRIPTION OF THE DRAWING

A preferred embodiment of the present invention is described herein withreference to the drawing wherein:

FIG. 1 is a perspective view of a test subject engaging in a testprogram in accordance with a preferred embodiment of the presentinvention;

FIG. 2 is a second perspective view of a test subject engaging in a testprogram in accordance with a preferred embodiment of the presentinvention;

FIG. 3 is a view of the test field showing a fixation target and twotest symbols, and identifying the blind spot region;

FIG. 4 is a chart illustrating generally the overall flow of the testprogram of the preferred embodiment of the present invention;

FIG. 5 is a chart showing generally the flow of the preferred setuppretests and vision pretests;

FIG. 6 is a chart showing generally the flow of the preferred displaymonitor and ambient lighting pretests;

FIG. 7 is a chart showing generally the flow of the preferred blind spotpretest;

FIG. 8 is a chart showing generally the preferred flow of the colorcontrast acuity pretest;

FIG. 9 is a chart showing generally the preferred flow of the multiplesuprathreshold test;

FIG. 10 is a chart showing generally the preferred flow of each of thecentral, nasal, and temporal single threshold tests;

FIG. 11 is a chart showing generally the preferred flow of theinteractive test subject instruction provided by the preferredembodiment of the present invention;

FIG. 12 is a chart showing generally the preferred flow of the fixationdetector aspect of the present invention;

FIG. 13 is a chart showing generally the preferred flow of the cursorcorrection feature for the fixation detector aspect of the presentinvention;

FIG. 14 illustrates a preferred distance prop for use in adjusting thetest subject's position in front of the test field;

FIG. 15 shows a card that is used in the preferred embodiment of thepresent invention to help establish the appropriate ambient lightingconditions of the room in which the test is conducted;

FIG. 16 illustrates the preferred fixation target in the multiplesuprathreshold test having two targets momentarily flashed on the planarsurface, and a cursor mark properly positioned within the fixationtarget to allow progression of the test;

FIG. 17 illustrates example floatation of the fixation target;

FIG. 18 illustrates example temporal movement of the test symbol duringthe preferred embodiment of the blind spot pretest;

FIG. 19 illustrates an example event of the preferred color contrastacuity visual pretest;

FIG. 20 is a chart showing generally the flow of the preferredprofessional mapping embodiment of the present invention;

FIG. 21 is an example visual field map with numerical and colorrepresentations at each field point to indicate the test subject'sthreshold point at the various visual field locations;

FIG. 22 is a chart showing generally the preferred flow of the displaymonitor color calibration procedure of the present invention; and

FIG. 23 is a color spectral range line that is used in the preferredprogram to help color calibrate the display monitor.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The preferred embodiment of the present invention is a color vision andperipheral color contrast field threshold test that is embodied ininteractive computer software. Specifically, color vision and colorcontrast techniques are used to test a relatively large number of cone,or color, receptors at and above threshold for peripheral vision. Smallcolor contrast differentials are presented to the test subject usingrelatively large, flashed symbols 8 to test for loss of peripheral colorcontrast discrimination. Threshold is a function of degree of colorcontrast discriminated rather than test symbol size.

Peripheral field testing using contrast methods is not new. Sinusoidalgratings for contrast sensitivity testing of the visual field, bluestimuli on yellow backgrounds, and low color contrast testing using theperipheral ring of Arden, for example, have all been used previouslywith success. Color testing may use a less robust system involving alower volume of neural pathways, and provide an earlier indicator ofdisease. Blue on yellow testing combines some of these potentialadvantages, but typically tests threshold with variation of stimulussize. The yellow background isolates blue cones, but the ability of bluecones to detect stimulus size may not be as sensitive as testing furtherfor color discrimination as a threshold measure.

The vision screening system described herein attempts to go yet a stepfurther by testing cones for color discrimination which have beenbackground adapted. It is believed that such testing can be moresensitive than stimulating cones with an easily-detected wavelength towhich the test subject had no previous adaptive exposure. Certainadvantages may therefore be obtained by testing the peripheral fieldbased on the test subject's ability to detect flashed symbols ofincrementally-varied color relative to a colored background. Preliminarytesting of this system suggests, for example, great sensitivity fordetection of diabetic eye disease and glaucoma.

Indeed, test results indicate that the highly localized discriminativetesting of peripheral loci in accordance with the present inventioncreates a sensitive self-test. There is a considerable reduction inability to detect color contrast of specified levels in even early eyedisease compared to age-matched normals. This allows selection of pointsjust above such thresholds as part of a self-test that can sensitivelydetect early eye disease. Further, such points could be age adjusted.Indeed, tests conducted in accordance with the present inventiondemonstrate a considerable difference in discrimination between normalsand most early glaucoma patients. To allow effective self testing, thissensitivity is quantitized and converted in the preferred embodiment ofthe present invention to a score, to provide an effectivepass/fail/borderline/retest screening test format.

The preferred color vision central and peripheral color contrast fieldthreshold and suprathreshold test is conducted using conventionalcomputer equipment, such as a home personal computer system 1 forexample. As shown in FIG. 1, the computer system 1 preferably includes aCPU 2 providing higher level sound and graphic capabilities (including,for example, a video card that provides 32,000 or more colors), akeyboard 3, a computer mouse 4, and a high-resolution color monitor 5having, for example, 600×800 pixel resolution. It will be understood,however, that the present invention can also be carried out using othermore conventional video equipment, such as a television display monitorand video tape or laserdisk player, interactive 32-bit game cartridge,or the like.

The preferred test program combines the merits of sensitivity of lowcolor contrast testing with geometric symbols 8 positioned throughoutthe visual field to result in a map 120 of the color contrastsensitivity of the test subject's field of vision. In particular, thepreferred test program tests a field where α is about 27 degrees (nasaltest) and 25 degrees (temporal test), whereby approximately 100 gridpoints are tested. The preferred test program allows the locations ofthe particular points tested to be adjusted if desired.

The preferred test program begins by soliciting and recording the ageand/or birth date of the test subject 9 at step (10). As with mostvisual field testing, there is a decline in symbol recognition, that iscolor contrast detection ability, that correlates well with age. Thepreferred embodiment uses two methods to accurately account for thischange. First, five separate sets of test symbols are used: one set forages up to 50; a second set for ages between 50 and 55 (with increasedcolor contrast by one increment, as defined below); a third set for agesbetween 55 and 70 (with increased color contrast by yet anotherincrement); a fourth set for ages 70 to 85 (with increased colorcontrast by yet another increment); and finally a fifth set for agesover 85 (with again an increased color contrast by yet anotherincrement). Second, scoring is adjusted based on age, and statisticalcomparisons that have been made with normals and early glaucoma patientsfor example. The age of the test subject is considered in the analysisportion of the test program at step (70) for the purpose of moreaccurately screening for the presence of eye disease. Age adjustmentswere determined using a professional prototype test to quantify colorcontrast thresholds at each grid test point to construct thresholdpoints. Whereas the conventional definition of threshold is detection in50% trials, the steep threshold curve observed for this test, and thedesire for a screening test, led to incorporation of pointsrepresentative of detection in about 95% of trials.

Other preliminary information may be recorded at step (10), such as thepatient name, patient sex, test date, test time, and test versionnumber. The filename in which the test results will be stored may alsobe noted for the test subject 9.

The preferred test program continues whereby the test subject 9 is giventhe opportunity to select one of three possible test format; a firsttest format that tests the left eye, a second test format that tests theright eye, or a third test format that tests both eyes. Alternatively,the default may be for the test program to test both eyes without givingthe test subject an option.

The test subject 9 then practices following a moving or "floating"fixation object 11 that moves alternately about 100 pixels verticallyand horizontally in a repeating fashion. In particular, the test subject9 is required to move the cursor 125 associated with a computer mouse 4in synchronization with the moving fixation object 11. The test taker 9is placed a predetermined initial distance D using for example ameasuring tool or distance prop, as discussed further below, suchinitial distance varying depending on the particular monitor 5 size inuse. The blind spot of the test subject 9 is then determined using aperipheral target 29 that slowly travels temporally away from thefixation target (step (100). The distance D is adjusted so that theblind spot of the test subject 9 is affixed in the same relativeposition on the computer monitor 5 for every test taker 9, allowing the27 degree field (nasal test) and 25 degree field (temporal test) to beobtained. If no blind spot is found, the test repeats slightly below andthen slightly above the fixation object 11. Once the blind spot isidentified, the test taker is instructed to adjust the distance prop aspecified number of units, and then to use the distance prop toaccurately position the test subject 9 in front of the computer monitor5.

As shown for example in FIG. 11, these or other similar instructions arecoupled with demonstration and optional trial runs whereby the testsubject 9 is given the opportunity to become better acquainted with theparticular test format and requirements. The test program may monitorand interact with the test subject 9 during this time to provide thetailored guidance that the test subject 9 appears to require to becomesufficiently comfortable with the testing format and requirements. Suchguidance may include instructions (81), demonstrations (82), and/ortrial runs (83) that are repeated as interactively deemed necessary(step 84). Any instructions and/or other notices (81) intended to bedelivered to the test subject 9, either before, during, or aftertesting, may be provided in the form of printed materials, or may bepresented to the test subject using text, graphics, video, speech and/orother audio representations generated using the graphical and audiocapabilities of the computer system 1.

The preferred test program is based on a theme that is intended to makethe test program more entertaining and less intimidating for the testsubject 9. A more relaxed and comfortable test subject 9 is likely toresult in more accurate test results. Moreover, test subjects are moreapt to conduct a self test if the testing environment is friendly andentertaining.

The preferred test program generally calls upon the test subject 9 toidentify the appearance of various colored targets, or marks 8, that aremomentarily displayed, or flashed, at various locations on the testfield 14 on the computer monitor display 5. The target flash ispreferably for a period of approximately 50 milliseconds. To keep withthe theme of the test program, the various targets or marks 8 may berepresented as objects, such as "quarks," "anti-quarks," satellites,planets, spaceships, or the like traveling through space for example.Throughout the test program these marks 8 appear, either alone or incombination with others, at various locations on the test field 14displayed on the computer monitor 5.

These marks 8 preferably have a generally annular diamond shape or asolid diamond shape. The marks 8 constitute a region of color that iscontrasted against the color of the test field, or background 14. Inthis way the marks are low color contrast symbols 8, or for example, areregions that have a change in the proportion of the primary additivecolors that constitute the background 14, so to create small incrementsof detectable change in color. The degree of contrast used to developthe test range included 17 contrast increments as follows: 3%, 5%, 7%,10%, 15%, 20%, 25%, 30%, 40%, 50%, 60%, 70%, 80%, 100%, 120%, 140%, and200%. Color hue was set using rgb values, and programs measuring colorcontrast. There is not necessarily any significant difference inluminance, or black/white contrast, between the mark 8 and thebackground 14 for most test symbols 8. There is increased luminance,however, in the preferred embodiment for increments beyond 100%contrast.

The presence of a flashed object reaching a peripheral receptor isdiscriminated most easily as having color contrast relative to a coloredbackground by healthy receptors. In the presence of various eye diseasethese receptors lose sensitivity to detect color, color contrast, andwhite light on a white background. All such symbols, and more, can beused to sensitively test for peripheral vision health. The presentinvention uses peripheral color contrast as a readily available andaccurate method for use with personal computers, television monitors,interactive game cartridges, video conversion, and the like.

Specifically, the test program tests the subject with nonvarying 90 mm²targets 8 of varying color contrast. For most test increments this meansvarying rgb values relative to the background so that the luminance isconstant but the hue--the rgb components--is varied, in contrast to moreconventional visual field tests which typically present targets ofvarying size. The flash speed for the presented symbols 8 of thepreferred test is a constant, and the targets 8 presented are all thesame size. It is rather the color contrast relative to the background 14that determines threshold and ability to distinguish the symbol 8 fromthe background 14.

While the center of each target 8 is spaced no closer than approximately1.5 degrees of field separation, due to the size of the test symbol 8and reliance on color contrast for the detection variable, the testareas nearly abut one another. At threshold, the preferred test programtests a larger retinal area than conventional tests that vary stimulussize using a target of 90 mm² on a 17" monitor versus 7 mm² for atypical 3 mm diameter white test symbol on a Humphrey 24-2 rather thancolor contrast. Further, the presentation of such color contrast symbols8 in a momentary flash appears to be quite significant, insofar as afirst target that differs from a second target by only 3-5% colorcontrast will be discerned with greater difficulty as the flash timebecomes shorter. The color contrast symbols 8 may be used alone, or incombination with black and white, or luminance, contrast symbols 8. Thepreferred test program, however, employs only color contrast symbols 8.Indeed, the peripheral targets or marks 8 have a decrease in bluesaturation and are displayed against a purple background 14 (rgb value153 0 153). The color contrast presented by this color combination isdeemed to provide enhanced sensitivity to the test. An alternative coloraxis for color contrast may be used, such as in the television monitorembodiment for example, whereby the marks 8 are increased in bluesaturation and displayed on background 14 that is 0 153 153. Abackground 14 of two primary additive colors could represent yet anotheraxis. It appears as though such color contrast combination also provideseffective sensitivity to the test. All three color axis can be also beused effectively in this manner (red-blue/purple background;blue-yellow/green background; red-yellow/orange background).

PRETEST

The preferred test program begins with a short series of individualpretests (20) and (30) that are conducted to help the test subject 9assess and/or adjust the testing environment for maximum effectiveness.These pretests consist of setup pretesting and a vision "pretest." Thesetup pretests (20) include monitor adjustment and calibration (21) andlighting adjustments (23). The vision pretests (30) include a firstblind spot pretest to make an initial adjustment for testsubject-to-test field distance (27), a second blind spot pretest todouble-check the blind spot location (31), and a color contrast acuitymeasurement (35), useful as a general measure of visual health. Thepreferred test program has an option for adjusting the symbolsensitivity (degree of color contrast) (39), either manually orautomatically in response to the color contrast acuity measurement (35),to recalibrate the color contrast used with the particular test subject9 so as to provide added flexibility to, for example, monitor the fovealvision of the test subject. The inputted age of the test subject, fromstep 10, is also preferably used to calibrate the color contrastsensitivity used during the test program.

For example, a first setup pretest (21) helps the test subject adjustthe color, contrast, and brightness of the computer display monitor 5.As shown in step (22), these variables may be adjusted with the aid ofstandardized colors and gray scales, which may be provided to the testtaker as part of a brightness standardization for ambient light as asoftware adjustment, or on cardboard strips for example, against whichthe color and brightness displayed by the monitor 5 are compared.

Preferably after the contrast and brightness of the monitor 5 areadjusted, another setup pretest (47) may be used to calibrate the colorsdisplayed by the monitor 5. The preferred calibration procedure is setforth in FIG. 22 for example. Instead of using costly or specializedhardware or software to adjust the colors displayed by the monitor 5,monitor color is adjusted in the preferred embodiment of the presentinvention through the use of a finely incremented horizontal line 135that is displayed on the computer monitor 5 (step 140), as is shown forexample in FIG. 23. The horizontal line 135 provides a color spectralrange from "bluish purple" on one end of the spectrum, to a "reddishpurple" on the other end of the spectrum. Hues vary from about 250-350in single increments, wherein a hue of 300 is equal to an rgb value of153 0 153.

The test subject is advised to view the horizontal line 135 for thepurpose of identifying two locations on the line 135; (1) the locationwhere the test subject perceives a spectral change from a "bluishpurple" color (more purple than blue) to a mostly blue or dominantlyblue color (point A); and (2) the location where the test subjectperceives a spectral change from a "reddish purple" color (more purplethan red) to a mostly red or dominantly red color (point B). These twolocations may be identified (step 142) by the test subject using acursor mark under the control of the computer mouse 4 for example.

Once the two locations have been identified by the test subject, thepreferred program bisects the two selected locations (A) and (B) alongthe spectrum to identify the spectral point (C) that is considered thetruest color purple--equal parts blue and red--as displayed on theparticular computer monitor 5 being used (step 144). This point mayshift dramatically from a high Kelvin (temperature setting of amonitor), i.e. 9300, to a low Kelvin, i.e. 5000, and gradations inbetween. Addition or subtraction of blue across the entire spectrum, forexample, can then result in a controlled shift along the length of thespectrum of the equally balanced (red versus blue) violet region (C) toa predetermined point that is a constant for all calibrations (step146). In this manner the relative settings from one monitor to anothermonitor will vary only negligibly.

In a similar manner, a finely incremented horizontal line displaying aspectral range from "greenish yellow" to "reddish yellow" can bedisplayed and adjusted, to more completely calibrate the monitor. Thepreferred program thereby can detect the relative gains of both greenand blue relative to red, and the information is then used to adjust therelative settings of blue and green relative to red for all colorswithin the color palette of the vision test. No color match swatches orthe like need be used.

If desired, the test program may first present to the person calibratingthe monitor 5 a display of all 17 contrast increments used by the testprogram, so as to help check whether the person calibrating the monitor5 can perceive the various contrast increments. This operation helps toprovide appropriate monitor color calibration.

A preferred method to control ambient light (23) uses a card 6 withluminous material 7 adjacent to high contrast print 28, functioningeffectively as a light meter. The card 6 is optionally provided with thepreferred test program materials to help the test subject 9 adjust thelighting in the testing room to an appropriate level. The testing roomshould not be either too dark or too light. The preferred light metercomprises a light-colored card 6 constructed from cardboard that has aspot approximately one inch in diameter of luminescent material 7, suchas luminescent paint for example, located in the center of one side ofthe card 6. Printed in fourteen point bold print on the light-coloredmargin surrounding the luminescent material 7 are instructions 28 thatadvise the test taker 9 to first position the luminescent side of thecard 6 against or adjacent the display portion of the computer monitor 5for a specified period of time (24). During this time the luminescentmaterial 7 absorbs a sufficient amount of light radiation to allow thematerial 7 to glow in lower light levels. The test subject 9 is nextinstructed to turn the luminescent side of the card 6 away from thecomputer display 5 (step 25), and to adjust the lights for simultaneousperception of a glow of the luminescent material 7 and visibility of theprinted instructions 28 on the card 6 (step 26). It will be understoodthat other appropriate symbols may be used on the card for this purposeinstead of the printed instructions. The resulting control of lightlevel range in the testing room will enhance the overall accuracy of thetest program results. Alternatively, the appropriate lighting levels canbe set with the aid of a photodetector. The preferred light level forthe testing room is sufficient to barely read the luminous dial of awatch.

The vision pretests commence with a first blind spot pretest (27) thatidentifies the monitor size and recommends a starting distance for thetest subject 9 to begin testing. The accuracy of the screening test ofthe present invention is maximized if test subject 9 is properlypositioned in front of the testing field 14. An initial distance of 14"between the test field and the test subject is recommended for astandard 17" monitor 5. This initial distance is increasedproportionally for larger monitors. At these distances, the preferredtest program tests a field where α≅27 degrees (nasal test) and 27degrees (temporal test); 15 horizontal increments with approximately 1.7degrees each.

Proper positioning of the test subject 9 in front of the monitor 5 canbe approximated using a measuring tape or an alternative measuring toolor distance prop. Alternative distance props may include, for example, aspecified length of nested foam drinking cups that bridge the gapbetween the test subject's upper chest region and the test field 14.

Another alternative measuring tool 13 may comprise a modified eyewearframe 15 wherein the bridge portion of the frame includes a one-inchvertical slit 19 to accept a string 16. One end of the string is affixedadjacent to the test field 14, such as through the use of a flat plate18 secured to the display monitor 5, using adhesive tape, a latch andhook material arrangement, or the like, either above or below the testfield 14. The string 16 includes a series of numbered or color-codedprotuberances 17 spaced approximately one inch apart, which allow thestring 16 to be securely snapped and retained in position on the eyewear15 at varying lengths. In this way a specified length of string 16 canbe secured to the eyewear 15 so as to, when worn by the test subject 9such that the string 16 is relatively taught, provide an approximateseparation distance D required for the selected display monitor size. Acorrelation between the selected display monitor size and theappropriate protrusions 17 to be used to secure the string 16 to theeyewear 15 can be provided to the test subject 9.

Instead of requiring the use of a distance prop, an alternative initialblind spot pretest incorporates a stationary blind spot color contrastsymbol 8 that flashes within region 12 of the test field 14. The testsubject 9 appropriately positions himself or herself in front of thetest field 14 such that the flashing symbol 8 is within his or her blindspot and can no longer be perceived. In this way the test subject 9 isproperly positioned for the testing and can be analyzed against dataobtained from normals.

More accurate refinement of the starting distance D of the test subject9 from the test field 14 is accomplished through a second blind spotidentification pretest and position adjustment (31). Like the firstblind spot pretest (27), the second blind spot pretest (31) can berepeated at any point in the test program, if desired, to ensure thatproper placement of the test subject 9 is maintained throughout the testprogram. The purpose of the second blind spot test (31) is to helpensure that nasal margin of the blind spot is affixed to the same region12 of the screen for each test taker, each time the test is taken. Thisimproves test consistency, and allows testing of a central field where ais 20-25 degrees, and a peripheral field where α is about 27 degreeswhen the fixation target, or fixation detector 11, is moved off center.Moreover, placement of the region 12 at one-quarter the distance acrossthe width of the display of the monitor 5 allows a 25-degree field to betested when the fixation detector 11 is placed in the center of thedisplay.

Vision Fixation Detector with Fixation Enforcement

It is widely known that proper fixation of a test subject is a criticalelement to any side vision test. The preferred test program attempts tocapture the concentration and focus of the test subject 9 during thecourse of testing by requiring the test subject 9 to position andmaintain a cursor mark 99, the position of which is controlled throughthe test subject's manipulation of the computer mouse 4, within theregion of the fixation detector or target 11.

In all vision tests involving side or peripheral vision testing, afixation monitor or detector 11 is displayed in the center of the screenagainst a purple background 14, as is shown for example in FIG. 16. Apair of cross hairs 99 are disposed at the center of a black ring 97.Together the ring and cross hair arrangement constitutes a fixationdetector 11 and enforcement system. In particular, the detector in thepreferred embodiment consists of a well defined black circle 97 of about0.5 inches diameter (in the center of which is the desired point offixation), central yellow dot or zone 98 of about 0.25 inches diametercentered within the ring 97, and four peripheral radial arrows 96pointing inward and touching tangentially the defined ring 97. Centralcross-hairs 99 are superimposed over the yellow dot 98, such cross-hairsmoving in synchronous fashion with movement of the computer mouse 4.

More particularly, the mouse cursor is synchronized to adjust thelocation of the cross-hairs 99 (the mouse cursor mark 125 is replacedwith the cross-hair mark 99). The cross-hairs 99 are initiallysuperimposed over the ring 97 and dot 98 configuration that "floats"(94) in a slow, repetitive vertical followed by horizontal motion. Thedefined circle 97 and central yellow dot 98 float slowly in a verticaland then horizontal range of slightly more than 100 pixels at 1 degreeper 3 seconds (slightly more than the diameter of the yellow zone 98);the result being the cross hairs 99 will not remain in contact with theyellow dot 98 unless the computer mouse 4 is constantly slowly beingmoved by the test subject 9 to stay in synch. This speed can beadjusted, if desired. Moreover, the region within the black circle 97preferably constitutes the entire universe in which the cross-hairs 99may be moved, regardless of the extent of movement of the computermouse, so that location and positioning of the cross-hairs 99 on theyellow dot 98 remains a relatively simple task for the test subject.Further, the size of the yellow dot 98 used is preferably larger inproportion to the higher age of the test subject.

Unless the test subject adjusts the cross-hairs 99 through manipulationof the computer mouse 4, the cross-hairs 99 will within a few seconds nolonger be placed within the central yellow dot 98 (step 86), and thetest is interrupted (87). The subject 9 must maintain the cross-hairs 99on the moving central yellow dot 98, a rather small region of the testfield 14, to avoid an interruption (87) in the testing procedure. Propercontrol of the mouse 4 causes the test program to proceed (93). Ifduring testing the subject 9 loses focus and, in turn, causes thecross-hairs 99 to stray away from the yellow dot 98 and approach theboundaries of the fixation target 11 (step (91), the fixation target 11flashes or otherwise indicates to the test subject 9 that the mousecursor is straying (step (92). If the cross-hair 99 is not thenrepositioned appropriately the testing is suspended (step (87) and thetest repeats itself (step (89) after appropriate instruction (step 88)to the test subject 9. Arrows 96 spaced around the outside of the blackring 97 point in an inward direction and arc or rotate around the ring97 as an additional visual aid that draws attention to the focusingtarget to indicate to the test subject 9 that the test subject 9 shouldbe prepared to maintain focus within the fixation monitor 11. Amechanism of this nature has been found to require a considerable degreeof fixation for completion of the test. It can be further cause toeliminate occasional glances away, by controlling the speed of thefloatation of the detector 11, and therefore the time it takes for across-hair 99 not being properly adjusted, to become out of sync.

As an additional aid, after each mouse click, as there may beinadvertent movement of the cross-hair cursor 99 from such a click, thecross hair 99 is automatically repositioned at its location prior to theclick as compensation for this movement. The movement is thereby morestabilized, and the use of the fixation detector 11 is more simplified.This sequence of events is illustrated in FIG. 13, and represented bysteps 61, 62, 63 and 64.

Conventional professional visual field tests in common use monitorfixation but do not induce or cause such fixation to be maintained. Thisnovel feature of the present invention assists effective testing ofperipheral vision, and aids in the desired accurate self-testrealization. Increased attention paid to the fixation target 11throughout the test improves the quality of the test results. Thismechanism is therefore incorporated into each test of the preferred testprogram.

Blind Spot Vision Pretest

In the second vision pretest of the preferred embodiment, the secondblind spot test (31), a blind spot mark 29 is presented for the testsubject 9 in the central portion of the test field 14 (step 32), andgradually moved temporally away from the fixation target in a horizontalmeridian about 2 degrees below the horizontal meridian of the fixationmonitor for each eye (in a direction as shown by arrow 100) (step 33).The direction in which the mark 29 moves depends upon the eye beingtested. If the right eye is being tested, the blind spot mark movestoward the right side of the test field 14. If the left eye is beingtested, the blind spot mark moves toward the left side of the test field14.

The test subject's responsibility is to indicate when the blind spottarget 29 disappears from the test subject's view as the test subjectsynchronizes the mouse 4 with the fixation detector 11. A click on acomputer mouse 4 is the preferred indicator for the disappearance of theblind spot target 29, although it will be understood that other types ofindicators may be used instead. The test is repeated if the blind spotis not found, altering the horizontal meridian by 5 degrees, first belowand if necessary above the original meridian, until the blind spot hasbeen identified. In this way the pixel coordinates of the blind spot areidentified, and then a distance adjustment advised, so as to fix thecoordinates of each test taker to a region 12 that is the same relativedistance between the monitor center and periphery. This ensures aconsistent, similar cone angle of testing for each test taker.

The second blind spot pretest (31) is used to ensure that the testsubject's blind spot located at a desired control region 12 of the testfield 14, or, in other words, is associated with a particular set ofdisplay pixel coordinates. In particular, if as a part of step (34) itis determined that the presented blind spot target 29 has notdisappeared from the test taker's field of vision by the time the blindspot target 29 moves beyond the desired blind spot region 12, then thetest subject 9 is advised to move closer to the display 5. On the otherhand, if the blind spot target 29 disappears from the test taker's fieldof vision before the blind spot target 29 reaches the desired blind spotregion 12, then the test subject 9 is advised to move farther away fromthe display 5 (step 36).

In this way the preferred test program identifies the nasal margin ofthe test subject's blind spot, and adjusts the test subject's positionwith respect to the test field 14 in an effort to obtain a relativelyconsistent set of pixel coordinates for all test subjects. Propermapping or fixing of the test subject's blind spot to the testing field14 helps ensure that the desired degree of field is tested, because thepreferred test program does not screen within a zone of about 2-4degrees surrounding the blind spot disc 12.

Based on the results of this blind spot test (31), the test programpreferably advises the test subject 9 to either move closer to or awayfrom the test field (step 36). An absolute or change in distance D maybe recommended by the test program, and may be expressed in terms ofinches or centimeters, or alternatively in units relating to thedistance prop, such as numbers of foam cups or specified protrusions 17on the eyewear string 16, for example. The blind spot pretest (31) takesapproximately 15 seconds to complete.

Color Contrast Acuity Vision Pretest

The vision color contrast test (35) comprises a series of targets ormarks 36 that are individually and sequentially flashed, each in amomentary fashion, on the test field within the black ring 97 of thefixation target 11 (step 38). The marks 36 are similar in shape to marks8 previously described, and may be varied in terms of color contrast.The test subject's response is received and recorded (step 41). If thetest subject's responses indicate that the test subject has failed thisportion of the test (step 42), then the test program terminates andappropriately warns the test subject (step 49). Otherwise, the testprogram may continue appropriately (step 48).

The initial targets 36 flashed on the test field in the vision pretesthave a strong color contrast relative to the test field or background14. As the test progresses, the color contrast of the targets 36relative to the test field 14 become weaker, so as to test thesensitivity of the test subject 9. Indicators, such as arrows 37, areprovided on the test field 14 to indicate to the test subject that thetargets 36 that the test subject 9 is required to spot during the courseof the test will appear in the center of the test field 14.

This test (35) allows a manner of testing that assesses the visualhealth of the fovea, or central vision region. It is known that contrasttesting, that is the ability of the central vision to discriminatedegrees of blackness relative to a background, is often reduced beforeloss of actual visual acuity in high contrast situations, such as thestandard vision testing in a formal eye examination known as snellenacuity determination. The ability to assess black and white contrast maynot be as sensitive a form of contrast testing as one that reliesinstead on ability to discriminate color contrast relative to abackground, with no change in "blackness" or "luminance". The currentinvention therefore assesses the color contrast discriminating abilityof the fovea, or central vision, by flashing objects 36 within thecenter of the vision detector 11, and requiring a response any time sucha flash is observed. Such testing allows identification of earlynonspecific loss of visual health, including color blindness, cataract,glaucoma, diabetic eye disease, and other diseases causing vision loss,in some cases being severely reduced while the test subject stillretains excellent vision in high contrast environments, and may not yetbe aware of a visual deficit. Rather than test for difference inluminance, as is typically done with conventional contrast testing, thepreferred embodiment tests the ability to detect difference in colorcontrast relative to the background for the central or foveal acuity.This may offer a more sensitive means of vision assessment, as cones maybe affected in their ability to discriminate color contrast beforeloosing ability to discriminate black and white, or luminance variation,as well as a relative measure of final acuity for pass, fail ormonitoring purposes. Varying color contrast through presentation ofdifferent flashed color contrast images 36 within the fixation detector11 achieves a contrast acuity testing of visual acuity (step 42). Thepreferred vision color contrast foveal test takes approximately 20seconds to complete.

Black and white or color contrast are both sensitive but non-specificindicators of disease, that are severely depressed when there issignificant loss of visual field. The color contrast sensitivity of thetest subject, as determined by the color contrast acuity vision pretest(35), may be used by the test program to adjust the color contrast ofthe test symbols 8 used during the remainder of the eye disease testsequence to a level that is deemed appropriate for the particular testsubject, as is shown for example in step (39) set forth in FIG. 5, foreither more accurate testing or monitoring purposes. The inputted age ofthe test subject, from step 10, may also be used to calibrate the colorcontrast sensitivity used during the test program.

Compliance

Moreover, by checking for false positive responses, false negativeresponses, and for fixation loss through presentation of symbols 8 inthe blind spot region 12, (steps 44 and 52 for example), the visionpretests, as well as the other tests in the preferred test program, mayalso be used to determine generally the aptitude of the test subject 9in taking tests of this nature. False positives are assessed by placinglarge objects, with nearly 200% color saturation, in or adjacent tofoveal vision. Failure to indicate awareness of this flash when it isseen, constitutes a false positive error. Measuring foveal colorcontrast vision in the preceding test allows distinction betweenextremely advanced eye disease and false positive, as it is knownwhether the test taker can discriminate the very high color contrastobject used for false positive compliance assessment. False negativesare assessed by placing sections within the test where no objects areflashed, and assessing whether any responses are made--acknowledgingpresence of a flash when none occurs would be known as a false negativeresponse. Placing objects within the blind spot region 12 assessed andadjusted to earlier in the test further allows monitoring of fixationcompliance. A further measure of false negatives is the number ofresponses made versus test symbols 8 or 36 presented--where for examplethe number of mouse clicks exceeds test symbols presented, in thepreferred embodiment the test subject may be instructed to retake thattest section, as too many mouse clicks are occurring. These testsequences are collated and scored separately as an indicator of testtaking accuracy, known as compliance, that is standard to peripheralvision testing.

Multiple Suprathreshold Testing

A multiple suprathreshold test (40) optionally follows in the preferredtest program to test for more advanced disease, insofar as one to threepoints well above threshold are selected for simultaneous testing. Thistest (40) takes only approximately two minutes to complete, becausetargets are presented in groups of one to three to allow for testing ofmany points in a short period of time. This test (40) is not included inthe preferred test sequence, as it essentially parallels the singlethreshold test (60) results that follow. It has the potential advantageof allowing screening of many points in a short time frame.

The multiple suprathreshold test (40) is optionally administered bypresenting the test subject 9 with a series of temporally-spaced,sequential events. Each event comprises a momentary and simultaneousflash of up to three targets or marks 8 presented on the test field 14(step 43). The individual locations of the targets 8 on the test field14 preferably vary from event to event, so as to ensure that allpertinent regions of the test subject's field of vision are sufficientlytested before the conclusion of the test (step 46). Moreover, the colorcontrast of the targets 8 presented within the same event may vary fromtarget to target. Similarly, the color contrast of the targets 8presented in two different events may be different.

The test subject 9 must try to discern the number of targets 8 presentedin each flash. After each event the test subject 9 must identify thenumber of perceived targets. The perceived number of targets for eachevent may be recorded between events through the use of a computer mouse4, whereby the test subject clicks a button on the mouse 4 in rapidsuccession; one click for each target 8 perceived (step 45). The testsubject 9 is preferably given a period of approximately 200 millisecondsfollowing the target flash in which to respond appropriately. In thispreferred embodiment, the computer system 1 keeps track of the testresults by monitoring the test subject's operation of the mouse button.

A complete multiple suprathreshold test (40) in the preferred testprogram consists of a succession of forty-three recorded events. Anydifferences between the number of targets 8 presented in a particularevent and the number of targets perceived by the test subject 9 arenoted.

27-Degree Nasal Test and 25-Degree Temporal Test

The preferred test program then conducts nasal and temporal singlethreshold tests (50 and 60) which test a field (α) of approximately20-27 degrees, thereby testing regions where some cases of earliestglaucoma change in the nasal test and/or tumor in the temporal test mayoccur. The preferred tests take only about 15 seconds each to complete.Placement of the fixation detector or target 11 is off-center asappropriate to increase the tested field (α). The preferred tests againmake use of the same fixation monitor 11 used in connection with theblind spot pretest. A purple background, or test field 14, is also used.Arrows 96 spaced around the outside of the black ring 97 point in aninward direction and arc or rotate around the ring 97 to indicate to thetest subject 9 that the test subject 9 should be prepared to maintainfocus within the fixation monitor 11. As with the other tests in thetest program, the test subject 9 is instructed to remain focused on thefixation target 11 during the course of the test. The requirement thatthe test subject 9 maintain the computer mouse cursor mark 125/99 withinthe fixation target 11 throughout this test and other tests helps keepthe test subject's attention focused, as described above.

In this test the black ring and cross-hair fixation target 11 describedabove is now presented in the vertical center of the test field 14, oron either the left side of the test field 14 or the right side of thetest field 14, depending on whether the test is nasal or temporal, andon the eye being tested. If the right eye is being tested 27 degreesnasally, for example, the fixation target is presented on the right sideof the test field 14. If the left eye is being tested in a similar nasaltest, the fixation target is presented on the left side of the testfield 14.

Only one target 8 is displayed for each event (step 51). The testsubject 9 is presented in the preferred nasal threshold test with onehundred and fifteen events, the series of events being presented in avarying temporally-spaced sequence (step 54). While remaining focused onthe fixation target 11, the test subject is required to indicate, byclicking once on the computer mouse 4 for example, when he or sheperceives an event--i.e, the appearance of a target 8 (step 53). Thetest subject's responses to each event is recorded, and any eventsmissed by the test subject 9 are noted. By moving the fixation target 11off center, testing beyond 25 degrees of field occurs. It is the goal ofthe preferred embodiment to test at about 27 degrees maximum, as mostuseful visual field information, particularly for screening purposes,occurs inside this cone angle.

Any points tested as a part of the nasal and temporal threshold tests(50 and 60) where the test subject 9 provided inaccurate test responsesare preferably retested at higher levels of color contrast, or atsuprathreshold levels, to help determine the degree to which the testsubject's vision is sub-standard at these particular locations (step56). Preferably the level of color contrast that is used to retest thetest subject 9 at these locations is adjustable, either manually orautomatically in response to prior test results.

Central Threshold Test

The test program concludes with a central threshold test (65) of thecentral 25 degrees. The central single threshold test (65) tests visionjust outside the fixation monitor 11 to about a 15 degree cone angle α,such angle being that made from a line 122 from the visual axis of thetest taker to the fixation detector 11, and a second line 123 from thetest-taker to the peripheral-most points being tested.

The test subject 9 is again required to focus on the fixation target 11and indicate, by clicking once on the computer mouse 4 for example, whenhe or she perceives the event--the momentary flash of a single mark 8.Instead of four rotating arrows, as in the multiple suprathreshold test,a single arrow arcs or rotates around the entire black ring 97 so as toindicate to the test subject 9 that he or she is supposed to, for eachevent, identify the appearance of a single target 8. The arcing of thesingle arrow about the ring 97 also indicates to the test subject 9 thatthe target 8 may be presented at any point on the test field 14. Testingin the preferred embodiment encompasses 1.7 degrees of separation, usinga grid of about 65 test points known to be most common to losses inglaucoma, but covering sufficient area of visual field to be useful inidentification of most forms of peripheral vision loss.

Again, any points tested as a part of the central threshold test (65)where the test subject 9 provided inaccurate test responses arepreferably retested at higher levels of color contrast, or atsuprathreshold levels, to help determine the degree to which the testsubject's vision is sub-standard at these particular locations (step56). Preferably the level of color contrast that is used to retest thetest subject 9 at these locations is adjustable, either manually orautomatically in response to prior test results.

The color contrast associated with the target flashes in any of thesingle threshold tests (50, 60, or 65) may vary from event to event. Theaverage color contrast of the targets 8 presented in the singlethreshold tests (50, 60 and 65), however, is less than the average colorcontrast of the targets 8 presented in the multiple suprathreshold test(40). In this way the single threshold tests (50, 60 and 65) are moresensitive tests than the multiple suprathreshold test (40).

The single near threshold central, nasal, temporal tests of thepreferred embodiment combined present the test subject with about 97sequential events, taking approximately five minutes to complete notincluding time spent with the interactive learning feature of thepreferred embodiment. Once again, the test subject's responses to eachevent is recorded, and any differences between the number of targets 8presented in a particular flash and the number of targets 8 perceived bythe test subject 9 are noted. Any missed points may be later tested atsuprathreshold, a higher color contrast level (step 56).

ANALYSIS

Previously gathered data is used to determine the various points thatshould be tested and the contrast that should be administered at thoselocations such that 95% of the normal population will discern thecontrast and identify that point. Since certain "normals" have modestvisual field abnormalities, the threshold points may alternatively beselected to be either higher or lower than 95% to more closely reflectdegree of Humphrey field loss. As there are some losses of sensitivity,reflex, and awareness due to age, adjustment of scoring can be maderelative to age as well.

Dynamic data exchange may be used to score the test results, permitanalysis of various test components, and to ultimately print out theresults if desired. A data base may be used to allow scoring of the testresults based on statistical comparison with large populations.

The test results may be presented in a variety of formats. For example,the test results may be presented by comparing the percent risk of eyedisease of the test subject to the percent risk of eye disease for thetest taker's age group. Certain test abnormalities, such as significantdeficit on the nasal test, are more likely to be glaucoma related. Testsubjects whose risk of eye disease, or more specifically glaucoma, isdetermined to be approximately average or above average can be directedto or presented with appropriate instructions and guidelines

The preferred embodiment of the present invention provides, based uponthe analysis of the quantified test results, one of the followingindications to the test subject: "low risk"; "borderline/suspicious";"high risk--professional evaluation required"; or "please retest--testnot taken with sufficient accuracy". The latter indication is given tothe test subject if the test subject's test compliance is deemed to bebelow average. The degree of test compliance is determined withreference to the test subject's particular variability in test results,incidence of false positive and/or negatives, as well as incidence offixation loss.

While the preferred test program is administered through the use ofconventional computer equipment, it will be understood to those of skillin the art that the present invention can alternatively be administeredand otherwise presented, without departing from the true spirit andscope of the invention, using conventional color television monitorsthat display information received from broadcast or cable transmission,from a videocassette or laserdisk player, or some other like source. Forthis alternative embodiment, the computer mouse button responsesdescribed above may be replaced with, for example, verbal responses thatare recorded by an individual acting as the test subject's partner, orby any other method that permits recordal of the test subject'sresponses for analysis.

Sensitivity and accuracy of the video format version of the presentinvention, however, can be maximized by using a blue/green format.Indeed, satisfactory results have been obtained using a 21-inchtelevision monitor that displays peripheral test objects of uniformsize, 0.75 inches².

A professional version of the test can be used in the medical officeenvironment in accordance with the present invention, and may be used inconjunction with a computer or with video equipment for example. Thepreferred professional test again presents a central fixation target 11,as described above, against a purple test field, or background 14. Oncethe test subject's blind spot location has been fixed to the desiredregion 12 of the test field, as described above, the test programproceeds to test 125 different peripheral vision locations on the testfield 14.

The preferred professional test uses a computer system to provide acomplete visual field test whereby 125 points in the visual field aretested sequentially and systematically with detailed quantification ofthreshold. The test is used to determine which of 14 increments of colorlevel (color contrast relative to hue of background) is the lowestdetectable color contrast for a given point in a visual field. The testis completed in approximately 4.5 minutes per eye for those withrelatively healthy visual fields, and less than 6 minutes per eye inmost other cases. A visual field threshold point map 120, such as theone shown for example in FIG. 21, can be displayed either on thecomputer monitor or printed in hard copy form, with the numerical valuesand/or color coding at each box or point tested to represent thethreshold or relative color contrast increment detected at thatlocation.

The preferred professional test consists of a series of identified gridcoordinates. Each grid coordinate or point has a predetermined andage-matched starting color level, as determined through testing ofnormals within the various age groups. These predetermined color levelsgenerally increase as the distance from the fovea increases, given thatthe threshold for detection of color contrast increases proportionally.The preferred test increases 3 color levels between steps, with eachstep constituting a 330 millisecond period in which a 50 millisecondflash of a color contrast symbol occurs 4-6 times over the 330millisecond period. The preferred test therefore ramps up 9 color valuesin about 1 second (3 steps). As soon as a flash is first detected by thetest subject, the test subject clicks a button on the computer mouse 4.Upon detection of this mouse click, the system ramps down from thedetected color level by 3 color level increments. The test thencontinues in the same fashion, commencing with this reduced color leveland having an increase of only 1 color value increment between stepsrather than 3 color value increments as before.

By way of an example, a test point may begins testing at a predeterminedcolor level of 4. A symbol having a color level of 4 flashes for 330millisecond at 50 millisecond per flash (step 110). During the second330 millisecond period, the color level increases to level 7 (113). Thesame flash timing and repetition rate is used. A color level of 10 isnext used for the third 330 millisecond period (113), and the same flashrepetition rate is again used. This continues until a test subject usesthe computer mouse to transmit an indication to the computer that theflash has been detected (111), or until the highest end of the colorlevel range is reached (112). If, for example, the test subject clicksthe computer mouse during the second 330 millisecond interval at colorlevel 7, the test stores the current level (114) and resets to colorlevel 4 and resumes the testing (115 and 116), this time increasing forthe second 330 millisecond period to color level 5 (119), and then colorlevel 6 (119). If a click then occurs (117), the current color level of6 is registered by the test program as the threshold for this test point(121). If no click occurs by the time color level 7 has been reached,the color level 7 will be recorded for the location (121).

Testing of all 125 points in this manner permits a threshold map 120 ofthe test subject's entire field of vision to be created for analysispurposes. Indeed, at the conclusion of the professional test a map 120may be presented to indicate the test results. The preferred map 120,which is shown for example in FIG. 21, takes the form of a grid in whicheach of the various squares of the grid represents a location on thetest field. Each square that relates to a tested location is filled witha number designation and color that each represent the test subject'sthreshold color contrast for that particular location.

For example, the preferred number scheme corresponds to the relativecolor contrast level increment discerned by the test subject at thevarious points tested, with the designation of "1" representing the mostsensitive increment discernable as previously determined in a clinicalsetting. These are the same type of relative increments as previouslydiscussed in the non-professional screening version of the test program.Similarly, green colors represent points that tested normal, while anorange color represents points that are suspect, and a red colorrepresents points that are problematical.

The preferred vision screening test programs described above,professional or otherwise, may be modified to test for diabetic eyedisease. Diabetic eye disease involves pathologic change to the retina,particularly that portion including the central vision, or foveal area,known as the macula. Diabetic eye disease causes macular dysfunction fora variety of reasons, including capillary drop out depriving visionreceptors of necessary nutrition, background retinopathy damagingmechanically and/or optically through hemorrhage, exudate, or swellingfrom fluid leakage; or proliferative retinopathy in which neovascularand fibrovascular tissue can cause distortion/contraction of maculararea(s) and/or bleeding.

In the preferred embodiment designed for the detection and monitoring ofdiabetic eye diseases, the test program that is described above forglaucoma testing purposes is converted to a macular field test, wherebya smaller cone angle is used to test only macular receptors. Macularreceptors are where diabetic eye disease often occurs, and indeed mustoccur before the disease compromises the very central acuity, or fovealvision.

Testing of the macular field for diabetic eye disease is accomplished inthis embodiment by positioning the test subject father away from thetest field than the distance required for glaucoma testing. In this waythe cone angle is reduced relative to the glaucoma test. The preferreddistance D between the test subject and the test field for the diabetesscreening is approximately twice the distance as determined by the blindspot pretest for the glaucoma screening. Doubling the separationdistance results in a decrease in tested cone angle from 25 degrees toabout 12.5 degrees. The use of a symbol presentation spacing thatcorresponds to the spacing required to place fifteen symbolsequidistantly across the test field provides for testing for each 1.7degree of field.

The optic nerve is approximately three millimeters in diameter, andrepresents about five degrees of field. The ability to test incrementsof one degree of field, as is provided by the preferred diabetes testingembodiment, helps to accurately detect macular pathology less than onemillimeter in diameter.

Enlarging the stimulus size, such as to 90 mm² for example, can furtherenhance the sensitivity of the test by testing a large number of coneswithin each degree of field tested. Since there is a considerable gapbetween the color contrast that may be discernable by normals versussubjects with early diabetic pathology, a highly sensitive test can beconducted by selecting field points which are just above threshold.

Although certain embodiments of the invention have been described andillustrated, it will be readily apparent to those of ordinary skill inthe art that a number of modifications and substitutions can be made tothe method for detecting the presence of eye disease in a human eyedisclosed and described herein without departing from the true spiritand scope of the invention.

I claim:
 1. A method for screening for abnormalities in the field ofvision of a test subject, comprising the steps of:focusing an eye to betested on a fixation target positioned on a colored planar surface;positioning said test eye a separation distance from said fixationtarget and aligning said test eye relative to said fixation target toenable testing of said test subject's peripheral vision by adjusting thedistance and alignment of said test eye relative to said fixation targetwith reference to a blind spot mark so that said blind spot mark is in ablind spot area outside of said test subject's area of central visionand is thereby removed from said field of vision of said test subjectwhen said test eye is positioned and aligned for testing; maintainingsubstantially said positioned and aligned test eye for the duration oftesting in order to maintain said separation distance and said alignmentof said test eye relative to said fixation target; maintainingsubstantially said focus of said test eye on said fixation target forthe duration of testing; and determining the visibility of additionalmarks employing the peripheral vision of the test eye, said additionalmarks being of low color contrast relative to said colored planarsurface to form color contrast symbols, whereby the presence of eyedisease is detected if said additional marks are not visible since theadditional marks are presented with sufficient color contrast on theplanar surface to be within the field of vision of a test subject's eyenot having the disease.
 2. The method of claim 1, wherein each of saidadditional marks is of the same size.
 3. The method of claim 1, whereinsaid additional marks are momentarily presented on said planar surfacefor detection by said test subject.
 4. The method of claim 3, whereinsaid additional marks are momentarily presented on said planar surfacefor approximately 50 milliseconds.
 5. The method of claim 4, whereineach of said additional marks is of the same size.
 6. The method ofclaim 3, wherein the planar surface is a display monitor.
 7. The methodof claim 1, further comprising the step of adjusting the lighting levelof the room in which the test is being conducted with reference to alight meter.
 8. The method of claim 7, wherein said light metercomprises a card having a region of luminescent material.
 9. The methodof claim 8, wherein said light meter further comprises a symbol printedon said card.
 10. The method of claim 9, wherein said symbol comprises aset of light meter instructions printed on said card adjacent saidregion of luminescent material.
 11. The method as set forth in claim 1,wherein the eye disease to be detected is diabetic eye disease, andwherein the separation distance between said eye of said test subjectand said fixation target is being approximately one meter, and whereinsaid color contrast symbols are presented in a region corresponding toapproximately a 10-degree cone angle.
 12. A method for screening forabnormalities in the field of vision of a test subject, comprising thesteps of:presenting to said test subject a fixation target positioned ona colored planar surface, so that said test subject may focus a test eyeon said fixation target and position said test eye a separation distancefrom said fixation target and align said test eye relative to saidfixation target to enable testing of said test subject's peripheralvision by adjusting the distance and alignment of said test eye relativeto said fixation target with reference to a blind spot mark so that saidblind spot mark is in a blind spot area outside of said test subject'sarea of peripheral vision and is thereby removed from the test subject'sfield of vision when said test eye is positioned and aligned fortesting; and presenting on said planar surface additional marks fordetection by said test subject using the peripheral vision of the testeye, said additional marks being of low color contrast relative to saidcolored planar surface to form color contrast symbols, whereby thepresence of eye disease is detected if said additional marks are notvisible since the additional marks are presented with sufficient colorcontrast on the planar surface to be within the field of vision of atest subject's eye not having the disease.
 13. The method of claim 12,wherein each of said additional marks is of the same size.
 14. Themethod of claim 12, wherein said additional marks are momentarilypresented on said planar surface for detection by said test subject. 15.The method of claim 14, wherein the planar surface is a display monitor.16. The method of claim 15, wherein said display monitor is connected toa computer and wherein the focus of said test eye on said fixationtarget is facilitated by requiring the test subject to maintain adisplayed cursor mark within said fixation target in order for the testto progress.
 17. The method of claim 12, further comprising the step ofproviding a light meter for reference in adjusting the lighting level ofthe room in which the test is being conducted.
 18. The method of claim17, wherein said light meter comprises a card having a region ofluminescent material.
 19. The method of claim 18, wherein said lightmeter further comprises a symbol printed on said card.
 20. The method ofclaim 19, wherein said symbol comprises a set of light meterinstructions printed on said card adjacent said region of luminescentmaterial.
 21. The method as set forth in claim 12, wherein the eyedisease to be detected is diabetic eye disease, and wherein theseparation distance between said eye of said test subject and saidfixation target is being approximately one meter, and wherein said colorcontrast symbols are presented in a region corresponding toapproximately a 10-degree cone angle.
 22. A method for testing thecentral vision of a test subject, comprising the steps of:placing markscentrally on a planar surface, said central marks being of low colorcontrast relative to said planar surface; and determining sensitivity ofsaid marks through direct viewing by said test subject through directviewing of said marks.
 23. A method for screening for abnormalities inthe field of vision of a test eye of a test subject, comprising thesteps of:focusing said test eye on a fixation target positioned on acolored planar surface; and determining the visibility of objectsflashed on the colored planar surface in the peripheral field of visionof said test eye, said flashed objects being of low color contrastrelative to said colored planar surface to form color contrast symbols,whereby the presence of vision abnormalities are detected if saidflashed objects are not visible since said flashed objects are presentedwith color contrast on said planar surface so as to be within the fieldof vision of an eye not having any abnormalities.
 24. The method as setforth in claim 23, wherein at least one of said flashed objects has adifferent proportion of color relative to said colored planar surface ascompared to other of said flashed objects.
 25. The method as set forthin claim 24, wherein said flashed objects are of a geometrical shape.26. The method as set forth in claim 23, wherein said colored planarsurface and said flashed objects are colored using primary additivecolors.
 27. A method for screening for abnormalities in the field ofvision of a test eye of a test subject, comprising the stepsof:identifying a peripheral field of said test eye relative to a coloredplanar surface; flashing objects at locations on said colored planarsurface within said peripheral field of said test eye, said flashedobjects being of low color contrast relative to said colored planarsurface to form color contrast symbols, and said flashed objects beingpresented with color contrast on said planar surface so as to be withinthe field of vision of an eye not having any vision abnormalities; anddetecting the presence of vision abnormalities in said test subject bydetermining whether said flashed objects are visible to said testsubject.
 28. The method as set forth in claim 27, wherein at least oneof said flashed objects has a different proportion of color relative tosaid colored planar surface as compared to other of said flashedobjects.
 29. The method as set forth in claim 28, wherein said flashedobjects are of a geometrical shape.
 30. The method as set forth in claim27, wherein said colored planar surface and said flashed objects arecolored using primary additive colors.